Milk product containing milk fat, and process of producing same



y 1 1953 c. A. KEMPF ETAL 2,638,418

MILK PRODUCT CONTAINING MILK FAT, AND

PROCESS OF PRODUCING SAME Filed July 3, 1952 2 Sheets-Sheet 1 nymvrons.

y 12, 1953 I c. A. KEMPF ETAL 2,638,418

' MILK PRODUCT CONTAINING MILK FAT, AND

' PROCESS OF PRODUCING SAME Filed July 3, 1952 2 Sheets-Sheet 2 umszvroas' zm mm 26 J fimazmdm? er,

b," P52240621", f,

MQJW z'l hisiimvention relates to a newanwimp'" product containing 'iiiilki rat which {is ar- Molnar-Ly :adaptedfor use in -tliehianiliaectuiie 0f mxious ifood products and is capable -cf impart- :proved by utilizing therein mflk'soil-ids inclugl g i partlally' hydrolyzed milk fat; as "fair as tlis'e 'xacids itherein produced bya controlled hydroly s Patented May 12, 1953 IMHJKIEPRODUGT CONTAININGMILK FAT,

cm) moesss nmraonecme =1SAME Ber eley, gley fs utnerlanfl fc Aubrey is ei h t ware Application July 3, 1ssa seriamofl2913291 lied "inga desiz' ed'flavor tosuch produeta Ihe product of this' invention, whenms'ed in athe production -of milk chocolate, imparts to ithe chccolate s; may :di's'tir-ictive and pleasing fia ver and taste.

invention also 'relates -"t'o a aew' and am- :proved prdcess, according as avliich the vil product herein referred to, may be produced.

mhis'application is a contmuaticn in-i rrt of applicants copending 7 application serial '-*No.

$695686, filed ilanuary 22, 1950',*-iorImproYements in Milk Product containing ltfilk Fat; and Free- :ess of Producing-Same, now abandoned.

Whereas-ithas been knewn-forsome years-that ,ithe' -flavor of 'c'ertain food products can {be imv applicants know, no onepsicrto the present invention has 'succeeded in producing, 011 mercial basis, a mill: preduet having ire fa y of the present invention. -"The a discovered that. whereas the resence-e v fatty adi'ds in milk gives a characteristics 'avor tdithemiil: which in "turn "imparts a "desi flavor-to certain products, such "as 'iniilk'c late, the preferred flavor requires controlled drolysis of the fats for the productioriof a par- '35 culat em inatianct riatty acids Whitxhii various fatty acids exist in particular proportions, and that it is necessary to avoid in the :finat product the presencepf certain ixiiw'afited catty acids which, cluded-,--eithf-" etc the" product an undesirabl flavor or exert-a depressing el fiect upon the desired flavor. 1

. 1 Accordingly;- iti-s amobjeettf irwentien ate-r prcvide a productef' the abwe descr iloed type which contains free fatty acids in combination and proportionsuch sisWi-ll' impart to redgct especially milk choccilate; -a "superior mi agsira-ble' "fiavor. .It isalso an-olpject ere'o {to provide aprocess according'to whicirm 115mg ucts ofthetyp'e ref erredtemay'besatisiaetemy 2 prcduced' on a commercial basis; v

1' The ,fact that fats- Which ave undergone-sen hydrolysisia re" capable" of a-fiecting "to" a 'rlotice sbie-dere he fla or 0f 'ctld ateg hasz been I *Enmfor a permaof at -1eastztwentyyeazrs.

has pee ecenuuetei y I "secret, and as a res'fil'tthereiis "very little to be at claims. (01. 99-56) 4a st nulat d '3; this -owiz1ede'ne, chocmate and .gi iry Lccmp mes have spemiargesums, foffiiohey Hort to develop a satisfaeterygmet ed ng milk ,fat prodii'ct YtOZbe used in th ciflaite to give to the J chocolate a desirable ;:11av r, er, an ether wares, that .fiav'oi'li ejferred toi tneart as'ahieh niilk nave-r. applicants m"):-sueieesem commer- 1a1 process has yet teen causes which involiis a cofitrelieemyareiym or "the tyiieiha'racter- As ar as .ist 9f thisinvention. Much ofth has 'beefl earri roundup the literature eon this s meet Apparenuy-netmuen iskncwn am an time in regarato the factors which enter iintoaild centrei the solution of this prcblem.

Amd'nQth earliest work onthissu eet was that ca led put-by 'Herberto. Otti'ng, the reaty. States *Letters Patent No. 1,966,460 and No.

@1 1 are disclosed in his rtwo United I Another worker inthis field was Herbert ,A. "Hollendergwhose experiments have been pube eonreetiener's Journal; issue of Noafter extensive experimentation, :the appli- --cants have made eefrftai'npbsei vatiens arid disceve'r' ies relating to the production '0: a roduct at the ty e lierere'ierred to. F rst; it has e'en ioiind that, ih-ofde r to ebtain the "desired flavor impact-ensues, the natural lipase contained in the 'xllillt to 'be processed must be empmyef i as the pl i-fl'ciiiil' 'iitillzed for the "hydrdlys'is atlviti and -that introduction of enzymes from other sources I "t6 li avoided, except "for possisiyaceemplismng a'minor amount of'thetotal hydrolysis; 1-1: .is runner foune hewever, that this fact' 'fneserits 'a difiliilt problem ecause as helieto'for known the "natural lipase in 'mill'i,

IWi-theut special ha'n'aline er assistance, will not "produce :rree catty acres in the quantities-requires within a time peried sufiiciently shaft to avoid 1 loacter iclcgical pei1aga new 't-hatmatte Within time 'pile'cl permitti g production p tides-accommodating=-tne-eiemands or many milks-apply; In eraer toeverecmethis difiieuity,

' ths eaapiieants have discovered {that certain drolysis treatment should be conducted at a relatively low temperature, that is to say, in the neighborhood of between 30 F. and 50 F. Due to the fact that the natural lipase activity in milk is apparently inhibited by the development of lactic acid by bacterial growth, the hydrolysis generally proceeds at this relatively low temperature at a greater rate than would occur at more elevated temperatures where bacterial growth is more rapid. This is especially true when the raw milk employed has a relatively large amount of tablishes a temperature condition where actual lactic acid producing bacterial present, as is the case of most manufacturing grade milk used in the production of milk powder. The utilization of this relatively low temperature for the hydrolysis treatment, therefore, constitutes one of the control factors which enables the hydrolysis to be completed within the time limit dictated by the above-mentioned factors.

In addition, it has been discovered that hydrolysis conducted at this relatively low temperature is productive of a free fattyv acid mixture or combination which diifers materially from the combination of free fatty acids produced at more elevated temperatures. For instance, at the relatively low temperature referred to, the

hydrolysis is productive of an increased amount of steam-volatile acids of both the water-soluble and Water-insoluble types, in relation to the amount of non-volative acids produced at such 7 temperature! The applicants have further discovered that an hydrolysis of substantially of fat to free fatty acids is approximately correct for a product possessing the, highest flavor characteristics. In addition, the fatty acids so produced should consist of a mixture made'up of volatile watersoluble free fatty acids, volatile water-insoluble free fatty acids, and non-volatile water-insoluble free fatty acids, all of which are present in predetermined relative proportions as hereinafter; set

forth.

It has also been discovered that by conducting the. hydrolysis treatment. at relatively low temperatures as hereinabove set forth, and byexercising certain additional controlswhich are hereinafter described in detail, the hydrolysis is carried out within a satisfactory period and, in addition, is productive of a mixture or combination .of free fatty acids present in relative quantities "aproximating the desired quantities for, each of the three'categories, respectively, with the exl'ception, however, that the volatile water-soluble acids and the volatile water insoluble acids are produced somewhat in excess of the amount productive of the best flavor characteristics. e

As a further step, however, the applicants have also discovered that such excessive production of the volatile water-soluble acids v and volatile water-insoluble acids is not objectionable provided that such portions thereof are subsequently eliminated from the fatty acidmixture. Consequently, and as a further step, this invention contemplates the removal of a limited quantity, of

the volatile water-soluble acids and the volatile water-insoluble acids in proportion to the non volatile water-insoluble acids by using asome what higher hydrolyzing temperature, the hythereof.

bacterial spoilage may result before hydrolysis is sufiiciently complete.

As additional controls to be exerted during the preparation of the milk for incubation and during the incubation period, the following practices should be carried out:

Clarification Prior to the' incubation of the milk, it is preferable to subject the milk to a thorough clarification treatment, particularly in those cases where the milk contains significant quantities of leucocytes. The purpose of the clarification is to remove from the milk certain inhibitory substances which are believed to be associated with leucocytes in the milk and which depress or inhibit the activity of the natural lipase of the milk. The need for such clarification will vary with different milks, but it is important in all cases to remove such inhibitory substances when,- ever they are present, as otherwise such substances act to seriously prolong the incubation period.

The removal of such inhibitory substances is preferably carried out in a centrifugal type of clarifier, as a thorough removal of such inhibitory substances is necessary for best results.

Furthermore, the clarification action should preferably be conducted at a temperature of approximately 65 F. Higher temperatures'impair the eificiency of the removal operation, and tests indicate that temperatures in excess of approximately F. should not be employed.

By actual test, clarification of a milk with an initially low leucocyte content caused an increase in the development of free fatty acids of only approximately 5% in a given period of time, whereas clarification of a milk with a relatively high initial leucocyte content caused as much as 50% increase in the development of free'fatty .acids in a givenperiod of time.

Control of concentration of fat in milk being treated his found that the concentration of fat'in the milk'being treated has a substantial efiec-t upon the rate of hydrolysis produced by the natural lipase present in the milk. The effect, however, is not so great in the early stages of the hydrolysis activity but is very marked in the latter stages In order to conduct the necessary hydrolysis within the permissible time period, it is necessary to utilize fat concentrations of approximately 12% or less. Actually, it is found to be preferable to use concentrations in the neighborhood of approximately 3% to 4%. For instance, a fat content of 3.7% is found to give excellent results and, in addition, to give approximately 28.5% of fat in dried milk powder which is the amount requir d by ih seq le e st for we em l i imwder, used .in the ,production-onmflk.chocolate. lii yiewjdfthe iactithatiltheihieherffat concentrat'ions .can be used .i'in'the early stages, .itiis ,poss'i- Tbljeflto "initiate the hydrolysis activity at .ooncenltratidns somewhat suh as, Iior iinstance, :concjentrations in the neighborhood or approximate'ly Such .concentrations, "however, .shoiild Znot-Joe used 'iorfimore than approxin fately fiue to [eight hours, and thereafter it is necessaryito suhstantiallylredncejthe nohceri'tra- ."tion'to' levfels below approximatelylz %.'.;as..otherwise 'theihydririlysis will v1 not go forward to com- .gpletion Within the "permissible "time meriold;

' Homogenizdtion v@It is h hl imp t nt marryin ==out this in-- ention -to :homogenize the im-ilk undergoing ttreatment after it :has been =-c1arifiedias @hoye gpointedoutand before :ismlhmihtedflo hydnoly, sis by the natural lipase of the milk. It isAtnow-n that hydrolysis aszefiected vby the natural lipase -Qf the milk progresses at a rather slow irate in -.unhomogenized milk, and thatpthe rate thereof :ismaterially increased'by homogenization. Ac- .cordingly, this process contemplates-an efficient homogenization treatment :according to when t-he parlticle size of the fat globules is reduced to an. :sizerof approximately three microns "or :less in adiameter. The smaller :the -,partic1e-,size-the hetter, wherefore the 'preterred practice is to'reduoe rtheefat :;globules -to sizes less than iapproximately i-ZfiWOLmiCIOIISK iH diameter.

ZEor the ,best, results, the homogenization should be sconducted Eat-the highesttpossible' temperature compatible with :the objectives of .the' process. .It ahappens, however, that-at temperatures around 12.09 5F.rsome destruction tor the :natural lipase of -lthe: -milksets;in,-wherefore it ispreferable to inatroduce the "milk into -the ihomogenizer at temperatures-which will cause it toemerge at atem- :perature of not substantially greater -than :-1I'5 According1y,-the vmillecan be introduced ,into the :homogenizer at temperatures :ranging from approximately 10391 :to 106 :F., with'the result that good homogenizing temperatures are reached without materially affecting the flipase iactivities.

Agitation known :that'the rate of I hydrolysis :that l-occursin :milk :by the ,action of the. natural lipase contained therein ;is retarded .as-ctheqconcentra- :tion of free :fatty acids, resulting from such bydrolysis, increases. This ifact. and the further ifact that it 1 is necessary to the :success .of the ;pr.esent: process to accelerate to the maximum extent gtherategof hydrolysis ,,make it important atoravoidtthe creation of high fatty acid concentrations within the localities {of the water-fat (interfaces where hydrolysis activity is occurring. Jhis.isibest-accomplished by subjecting thev milk, during the hydrolysis treatment, to agitation, particularly during the later stages -.of 'the "hyidrolysis treatment, when relatively large {guanitities. of free a fatty acids ,are present. Such :agitation serves to distribute throughout the -mass fof milk the tree fatty-acids formed duitingethe hydrolyiss and tothus remove suchaiaoidsi-rom the water-fat interface where .their presence would retard ,the hydrolysis-inlthe manner described. I

.Good agitation forthis purpose. isefiected by any Esl'litable .means which .will vigorously .carry. Qua-this objective; ,By way .or illustration, ,one method of accomplishingtthe ,desiredragitation. :is

to .recitculate the m k -durins h d oly is th means of a centrifugal working-near the llimit of its maximum-h ad pressure- Incubation temperatmes ,As statediahove, this;processinvoluesfthe utilization -of incubation temperatures fallin the .,.range of approximately 30 to approximately-50 ,F. It is, however, preierahleltohse temperatures, around.3,8 .to 410 2F. iThea tiliaattion-ofisuch relatively low temperatures not only roducesiatty acids in :the i desired combination hutialsc itJetards bacterial growth. it .will thos be :seen that the (utilization of .the lowfiemnetaturelhas the multiple advantage. of-

;a) Accelerating the roduction of the tree fatty acids;

@(b) Selectively promoting the hydrolysis "at" .pai ticulariacids to theenkiof pro ucing-tir d .sired .combinationor :,l1l l'KtU,1. e:-,0f .fIGQvffiglQtYfiQiflS in the. finished product;

' ,(c) gPermittin the hydrolysis-to hehconducted to the proper degree :without vproduction of in-- Lhibitory lactic acid from bacterial growth and (d) Establishing a temperature condition which is less favorable to bacterial spoilageldpra .ing the hydrolysis period.

Mme-o1 {incubation It is contemplated that hydrolysis tbezcarried :out; i or -.a period of .:,from approximately.{sixteen 'iiours approximately gsenenty-two gihours adeponding L011 "the .prevailing @conditi'ons. When :the :.:most favorable ieon-ditions are maintained, ia'isufiicient quantity 10f :i-free gfattyriac-idszoan be producedin axperiodiofirom approx-imateiyzsh teen hours to approximately ;twentylhours,;but when ;conditions are encountered-which are sless tayorable to the -maximum srate .of hydrolysis, lilonger periods are necessary. .Jrhe npperitin'i e limit of the incubation period is fixed ibyrthe extent I of ;ba c terial growth which occurs. .ziinsapiproximatelyseyentyetwo hours ssuch,-;growth;lin qereases to such zan.;extent ;tha t::-.further incuba- "tionx-is undesirable. in :oases :u'nuwl lich inlaid f1,- nation .is not practiced, aoraaeitation,iissmotuprac .ticed, or homogenization :is .;only :zinadequately carried :out, an increased :tim'e ofincuhationis necessary, sometimes iextendingz-ior :;a ;;period ;of as longzas .f-rom.'twentyefourzto;fortyeeightzhours, and possibly to the extent of the. maximum pe- 2121061 =;0f aseventy-two :hours.

In addition to what ihascbeen lsaidtaborent awill 'be appreciated that a;marked=advantage is realized :Lin the commercial production iof ::this product when the complete ,cycle ;of operation can be .conducted-withina period .of twenty-four hours or ,less, .as .suchpractice .enablesa sin le .setrzof .'.:p1ant equipment tube .usedn-dailyifonproces ins each :daily upplyof milk. =.,-Eor:.this-reason, it is particularly,-desirahle ,jbO fiXfifiClfifi $1,118 control ve stated to the end of accelerat- .ing the hydrolysis to the maximum degree.:and ,to conduct v-,con ip1eteoperations ,witliinva ,period of twenty-four hours or: less. v

HA5 .1 already pointed out the ,1 above-described hydrolysis process not ,only lends itselfrto satisfactory commercial practice which can he carried-out within the limited time requiredator the production of adequate quantities .of *free fatty .acids without spoilage .of the ,milkproduct, but, ,in. addition, it has 1 been ,discoyered rthat it provides ameans {for producing tree-jetty acids in ;-approximately the quahtitytratio rwhinh establishes combinations tor nmixtures of 45111211 7 acids productive of the best flavor characteristics in the finished product.

As previously stated, it has been discovered that the best flavor-bestowing properties of the milk of this invention require the production of free fatty acids in the three above-named categories, namely, volatile water-soluble free fatty acids, volatile water-insoluble free fatty acids, and non-volatile water-insoluble free fatty acids, and that according to the above-described practice the production in the first two categories is slightly excessive in relation to the production of the free fatty acids in the third category, as measured by the method hereinafter described.

As above pointed out, however, this does not provide any serious obstacle for the reason that these applicants have also devised a procedure by which the excessive portions of the free fatty acids in the first two categories can be eliminated, with the result that only free fatty acids productive of the correct combination remain. A better understanding of the nature of the results of the controlled hydrolysis referred to and of the removal of certain of the free fatty acids can be derived from a consideration of the following more detailed information.

One typical and illustrative example of the results of the hydrolysis conducted in accordance with the procedures of this invention is the following:

Whole fresh milk of approximately 4% milk fat content is clarified in a centrifugal clarifier at approximately 65 F. and thereafter homogenized in a two-stage homogenizer operating at a pressure of approximately 3000 pounds per square inch in the first stage and 500 pounds per square inch in the second stage. The milk is fed to the homogenizer at a temperature of approximately 106 F. and taken therefrom at a temperature of approximately 115 F. The milk is next cooled to approximately 38 F. and then held in tanks for incubation. During the incubation of the milk it is recirculated in the tank so as to agitate the same by means of a centrifugal pump which serves to circulate the entire volume of the milk at least once after the hydrolysis has progressed to a substantial extent. The incubation is thus continued for a period of twenty hours, after which it is heated and prepared for the treatment hereinafter described for removing the excessive portions of the volatile water-soluble free fatty acids and the volatile water-insoluble free fatty acids.

Such removal of the free fatty acids produced in excess can be effected by heating and flashing the milk into a vacuum chamber. According to this typical example, the milk, after it is taken from the incubation treatment, is heated to approximately 240 F. and then flashed through a valve into a vacuum chamber maintained under a vacuum of approximately twenty-nine inches of mercury. The flashing action may be conducted in an evaporator wherein evaporation productive of a concentrated milk product also occurs. This is desirable when a concentrated or dried product is sought, as is usually the case when seeking milk for producing milk chocolate. Accordingly, when a concentrated milk is prepared, either as the final product or as an intermediate product for subsequent drying, the evaporation can be continued and in such cases the flashing and evaporating treatments can be carried out in conventional milk evaporating equipment such as the multiple-stage evaporator. The elimination of the free fatty acids'produced in excess, however, occurs during the original flashing action, and such subsequent evaporation does not disturb the process. Proper elimination, however, of the excessive free fatty acids depends upon conducting the flashing in substantially the manner set forth, namely, by introducing the milk product at a temperature of from approximately 212 F. to approximately 280 E, into a. chamber having therein a vacuum of from approximately twenty-eight inches of mercury to approximately thirty inches of mercury. Lower temperatures can be utilized with the higher vacuum, and vice versa, and some variation may be effected according to the amount of free fatty acids to be removed. Furthermore, the particular temperature employed for flashing will vary according to the efficiency of the evaporating equipment being used, and for the more efiicient designs correspondingly lower temperatures may be used.

In the typical example referred to, after the milk has been flashed into the evaporator as described, a portion of the steam volatile watersoluble free fatty acids and a portion of the steam volatile water-insoluble free fatty acids are re moved. This removal by volatilization occurs in the vacuum chamber, with the result that the free fatty acids in each of the above-named categories remain in the product in quantities productive of the desired flavor characteristics.

The final quantities of the free fatty acids'remaining in the product are'establi shed after the removal by volatilization of approximately 21% by weight of all of the free fatty acids produced by the hydrolysis of the milk fat. Thus, approximately 38% of the volatile water-soluble free fatty acids and 19% of the volatile water-insoluble free fatty acids are removed by the flashing action. Thus, although the total amount of free fatty acids originally present constituted 442% of the fat before the flash volatilization, the total fatty acid content after'fiash volatilization constituted 3.50% of the total weightof the fat. Accordingly, the loss occasioned by the flashing represents '.92% of the total weight of the original fat.

It might be mentioned here that as evidence of the necessity to flash at the relatively high temperature referred to, tests have shown that a similar flashing treatment conducted at 180 F., that is to say, a temperature commonly used for evaporating purposes, does not produce any appreciable removal of the free fatty acids as required for the purposes of this invention.

Whereas the above specific example refers to the amounts of free fatty acids in the fat in terms of percentages by Weight, the more conventional method of identifying the extent of hydrolysis in actions of this type is by reference to free fatty acid degrees. Free fatty acid degrees is well understood in this art to mean the number of milliliters of .01 normal alkali required to neutralize the fatty acids in one gram of fat. The quantity of free fatty acids present in each of the three categories is determined by a steam distillation technique. The apparatus is similar to that employed in the determination of the Reichert-Meissl number as described in Official Methods of Analysis of the Association of Official '9 micromoles of fatty acids are extracted irom' the lipolyzed mt and distilled at a rate such that 300 milliliters oi distillate. are collected in a period of) approximately one hourf :As' expressed triglycerides the original fat rrcm which the fatty acids are produced. Sfiec-ifical-ly, sfi'ch fatty acids, whorl placed iii the three alcovename'dcategor-i'es, would be present in quantity in free fatty acid degrees, the combination of 5 substantially as follows:

AS EQUIVKEENT WEIGHTS 0F OLEIC ACID) -v Non- Volatile Volatile I latile Water 501- water msol- Yo Process Material 7 mubl l ub'l' meg? vtggig-giesglfatty acids fatty acids fatty acids mun I v W i P'efc'crit Percent Percent Cqmplete hydrolysis. Natural Butter Fat". 22. 67.26 10. btfi-n'ganfifiollendeh St'e'aps'ifi Lipblyz'li 28. 84 51.09 20.08

Cream lipolyzed at W 1 7,105? K. V 0tt1hg" Batt il separated 80.30 58.60 1l;10

. 20123 lipblyid s creamy 'Pfiis'invent1o11 m b peemgagw F; 57:89 26.65 46 wi -h a e D6; machete?! niilkaitr 50.00 28.83 21 .17

flashing.

aesrsay acids produced the hydrolysis-er the stove-stated typical examine; tasters mien-Haitian, isasfouows:

Volatile Water- Volatile Waterog-volatilei soliiblc' frc'e' irisolulile free ater-iqso'hihk mas acids fattylicids free fatty acids 1 iaed's ees si cgfes's 4'17 de'gl'es' or a total 19153014 degrees, which rpie's''rits 4.42 hydrolysis By weight.

After flashing; the comtniatica is rriies'eiit''d free fatty acid degrees as follows:

Volatile Water- 1 free 4 .7 de rees" 11.1 d'egfes' degrees or a total at 22.2 degrees, which" represehts the total amount of 3.50% free fatty acids' liy Weight in the'fatlanother factor conducting this: process, it

should b' lmowri' that the hydrolysis should not be conductedbeyor'id' the" point of convert-mg more than: approximately 69% of the fat-present ii-itdfree fatty' acids, vor morethan approximately 46" degrees. a lower limit the hydrolysis shoi'rld conducted: for apriod sufficient to scribed by (*Dtti-hg and: Hbllender, according. to

which temperatures are employed which; cause the fat to exist in meltea er-liquid state; results in the production of free fatty acids i-n which thequantities respactively,v at the comcomm acids. are presentmore approximately in the sam ratio as they existed in the form of The above-tableshewsth'e distributionbf free fatty acids in each categoryby equivalent weight expressed as oleic' acid, based on the total free fatty acids hydrolyzed: v

In-the combination of free fatty acids pro"- duced by the Otting and Hollender processes the acids are present in ratio similar to the ratio of; the fatty'acids as they exist in the form of triglycerides in the original tat; v H y Thus the on-volatilefatty acids wheniorihed lay an hydrolysis under conditions describedcby Otting andHollenderarepresent excess of-the vclatile' tree fatty acids-. 'Ihis is the reversepf the 1;'esults of hydrolysis conducted under th conditionsof the present invention, where" the volatile freefatty acids are formed in excess of the none-volatile free fatty acids;

Asa further typical and illustrative example may bementiened thefollowing: Milk is treated according to theprocedure constituting the first example, with-the exception that the hydrolysis is conducted to anextentsuflicient to produce thirty-fivefree fatty acid degrees.- After; flash-- ingitwill be Iound that a total 0f'26:1-5 degrees remainedin the prcduct made up of free fatty acidsfromeach of the three categories in" the following quantities-z hale Wate e l tt'isoluble free insoluble frce Water-insoluble fatty acids fatty acids s free fatty acids 1 14:94 degrees 7.01 degrees 4:20 degrees 1 traitsexampi the tie; Xample'rnay' be fen-swee e x (ima e-(saddened to eiiteiit" to s odiice; pert ijasl'i s, 2p'free raayaeid as:

as afte =1 sh nes-he free fatty acids iii pro-sea wnr be dammed" as renews:

s insolubleiree y cids' vcistue ad it;

1 6:6 degree-e f 1" Alt of the products produced in accordafi'ce withthis invention; When subsequently dried and employed in the manufacture of milk 'chocolatee impart ta the chocolate avery desirable ans pleasing flavor.

Volatile Water- Volatile Water- Non-volatile soluble free insoluble free Water-insoluble fatty acids fatty acids free fatty acids 13.95 degrees 5.69 degrees 2.65 degrees.

When that product was subsequently dried and employed in the manufacture of' chocolate, its flavor was characterized as poor, bitter, and'flat, and was devoid of the high milk flavor which characterizes the products produced according to this invention.

In the foregoing, where reference has been made to the particular combinations of free fatty acids, it is to be understood that some variation therein is contemplated to allow for Variations that occur in the characteristics of milk derived from different sources. It is known, for instance, that milk produced at different seasons of the year and under different feed conditions, and produced by cows of different breeds, will show some slight differences in the distribution of fatty acids existing in the milk fat. Consequently, some slight variation in the distribution resulting from hydrolysis will necessarily occur depending upon such variations found in the original milk being processed. What is said here, therefore, is intended to embrace such slight variation.

Milk produced according to this invention can be used with a high degree of success in the form Accordingly, the concentrated milk produced according to the procedure above outlined may be further processed for producing a milk powder. It is found, however, that the drying procedure employed ordinarily should be a spray drying operation like those used for drying whole milk powder. Drum drying methods are not satisfactory to provide the best results. If drum drying methods are employed for drying-the product of this invention, the finished product would be superior to regular unhydrolyzed drum dried powdered milk but it would be markedly inferior to the product resulting from spray drying. It should be understood, however, that'drum drying, if carried out under vacuum conditions, is much more acceptable than is the product which drum dried at atmospheric pressure. Furthermore, the moisture content should be reduced to a relatively low level, not to exceed approximately 3% to 4%, and preferably not more than approximately 2%.

As a further teaching with respect to this invention, it is here pointed out that the success of this invention as applied to whole milk powder depends upon maintaining a substantial amount of the dried fat particles in that particular associated relationship with respect to the non-fat solids in milk, known to the art as free fat relationship. It is understood in this art that various drying techniques exert different effects upon the associated relationship between the fat and the non-fat particles in a dry product, and that inv some instances the fat is more intimately attached to the non-fat solids than it is in other instances. When the fat is disposed in what may be regarded as a relatively loose association, whereby it is subject to being readily freed from intimate contact with the non-fat milk particles, it is referred to herein and in the art as being free fat. The existence of fat in the form here referred to as free fat is subject to being determined, by way of test, by direct ether extraction, and the term refers to that part of the fat which can be so extracted with ether directly from the powder. The remaining fat is non-free fat and is that which is sometimes referred to as bound fat. Bound fat can be extracted with ether only after the fat particles have been loosened by some suitable treatment, such as by moistening or steaming the milk powder.

Inasmuch as one of the major utilities of the present invention is found in its flavor-imparting characteristics, it is important to have the flavor which it imparts quickly detectable when milk chocolate made therefrom is placed in the mouth. Experiments have shown that the readiness with which the desirable flavor referred to can be detected is to a considerable extent dependent upon the degree to which the fat and its associated fatty acids present are associated with the nonfat solids of the milk in the form of so-called free fat. The amount of free fat that exists in dry whole milk powders now produced on the market according to commercial. equipment varies somewhat according to the procedure by which the powder is made. For instance, an examination of twenty-five dried whole milk products now supplied on the market by different manufacturers shows that the amount of free fat in the powder varies from 0.5% as the smallest amount up to 3.7% as the highest.

It is found that in order to produce the quicktaste response above referred to, the powder produced according to this invention should have fat present therein in the form of free fat in quantity of at least 4%, and with optimum results at approximately 8% and above.

According to this invention, in addition to the regular spray drying treatment employed for producing the powder, the milk should be further treated in order to be sure that it contains the requisite quantity of fat as free fat. In order to accomplish this result, the powder, relatively low in free fat as it comes from the drier, is passed through a fan or micropulverizer, or a muller, or any combination or all of these depending upon the amountof change that is required to convert the low, free-fat powder to relatively high, free fat powder. By actual test, the applicants increased the free fat in dry milk powder from the original amount of 2.03% to 9.62% by subjecting it to the action of a micropulverizer. Similarly, through the use of a fan, milk powder having an original free fat content of 2.48% was increased to 12.30%. In still further instances, a powder having an original free fat content of 3.18% was raised to a free fat content of 4.08% by subjecting it for one minute to the action of a muller; to a free fat content of 4.49% by subjecting it to the action of a muller for two minutes; to 5.93% by subjecting it to-the action of a muller for five minutes; and to 7.78% by subjecting it to the action of a muller for ten minutes.

The following table will serve'as a guide showing the relationship between the quantity of fat I azettee- 4 mnttaaf'tmei fatiamime nfim fleworin mow mndifled? pfoeediire asnweqoipfnent for carrying Very poor slow never-"developmen in; mouth prncduregan equipment? f cqncentfztingz ftoi sfiiw 'fltiifoydetefopmeiit in with-tilt ev p fifie the incubated" milk. I Fitzy121 Mi ly prompt flavor d'wei'opment mt R fegflng f0 t r wi g m verygo di' piom'pt fiovor dew' eibpme it-ihtfioutti I'ESBKGS E FEW storage tank where the mil-1%: Yegutggodtvery; prompt flavor de'velopmenli' tmbei-itreatedcan UGFHEIEFZIJ' ai-t'emperatui e-ofstp vim-nonevewpmmptn'mroimio mmem nficiith'a proximat y H' is a pump which seives' to e o t' i convey the-mini: thfdnglt'lihel2 fi dm=tfie-tafik l0 7 tom paiifiofeelcl' cletrifi'ers is and M which we ma mmdaw-imown' that?the presenee ofi' ati es: heres'hown con-heated series by the" line meteors more fmpottant tn tlie matn-iifleture ofi Th'e clarinet" m" is" connected y" in 6 t cfioeotete wheri tite-chox:oiattt-aw extensively warm-er? I 1 serves to heat the milk to a: dofihed cirpTeUessed to e suitstantitti 'degreep atu f ammo 'matei 103 to 166%": at Melange 01* 0'11: refining tone; refin gf momthe waifmer; themilit passes throughaa line; of chocolate servesvto develop an impfoved ffoyvor 20 w-td a sitrge tahk w zindithenc'e'to: em Homag cfmmeteristietfierein; Samantha-an mate to 't'hat eiitzet 2m homo enizin treatirrefit; the m e by, fifj'e fifsgfiQb! of m' misite amounts r milim subjeeteci te--a-pressure of sipp'ro'xi'mtttefyfree mat; and therefore?- the development: of 3060*190fifid8q sqfia ihehin thefirststa -tmf' f mt iii-the prodimt 'ismore importantrim the"- lpnr i'i m lti 'fiWpw S t r q f ih' h' iflth muftoturei of eho'eoIe-tein these "=ea;s'swfi'r second stage. extenst've-wfihihynot'empfoyedi It 'wilbbet The" milk passes from the ho'mogeniz'er 281 understood,,however, that la -providing through l into-wcooIer222 Themi-ikiemerge prodtrctii will impart" gdod new? oherecmg fro the homo-genizer Has a; temperature of terfsti'nst the nec'es'sityffc'ir su ch 'extensive refining" L approximately 112""F. to I18 1F3, and the cooler treatments is.reduced or eliminated. 27$Serves ta loring tfie temperature down-prepare The" spiny vdf'ieii: prod-net" ornament etceotdin t'ciryto'the incuhat I i-treatment; The milk loam to': tfiisti-nventionv er powdered mini containing ing the" cooi'er zwth'roug -hpipe 23* a temper mil'ie lipoiwzedi forth-ethos? pmt; byn-eltui' miikw'lipase containe-d in the mil-I i" while i'stim natural"? fiu-id state; anchoondiwt control confiitiorisipro-dia-ativemf"armdfjuste" pr at-suitahieoutfet; not-shown: f5 i's'a eentiifiigaf? dhtermihedfcomtiimtioh of free iettyacme Asem imp usedifor' re'circn'letihg tlie'n'fil'k' fd fi resuit -the difiTBn-t-cf'emseeoffatty name li'n 2 6 for the purpose of avgittttir'ig the some? 1y; the 'vofitti lewztter soihbie V'Gffiibt water zit is. at valvethe reeircufatin'g' line which" is? soli'iltiie; and" hon-volatilea: are pres 4W em ployedftoincrease-the Heed ofpressure-amsucfifreihtitemmnnnts=a;"to"-fa l s? thuswediiee the efii c'iency of'tfre pump. Ztisanr productive-of goo-1f. offfigh' mflk fizsvo'rr I t wi li agitator or ofieofe series: of agitatbrs" empi'oye'di arfswlie ohserved that the voiatfie acifis -prodirced in -the iheuhait'ifon and standemizztiow tank for" imexceseofthe d'esired"ratibs-aye Brought; purpose's asbove ofesc'ribedi- I theviratiosmrodi-mtiveefopthhnm never-Wham 4'5 Referring to Fi'gu-rez i it WflIb-e"lintedthattfie" evaporation; using-temperaturesabove Substen procedure and equipment is quite simflar;.. bift tTEHyTZIZ FL afld"pi'efrit51y ihrtfie oider ofb' tl iatT- i 'TEers thatF'w sparatbr i'wh'eis been in tweexrZKOWf and 26b F? Itiwil'i urthehbe noted treidu' intia tlie syetemimmediately aftef'the that the? pitidliictfifi finishe 011m" contains hea'itei-fl 'fi' and thate: separator serves tbrsepecrate notactit ewfimse anti/consequently f infihrfefl theoreatmfiom' the skim milk; AS a resuit'of hydrolysis-narrower i-n the pffidil fifl ih" these changesa the homogenizing treatment is stdra'geroitshipme t: impel-texttotiie creamomy andth'e hdmogefiiied Theiflhi'she-dvprodiiot contains the' wetler-sohr cream and skim milkareeith'er separateiyrcooler? bienmdu'cte'of'hydtoiysis including-the watteir'. Brought together for introduction; into the sol'uhie; portions" of? mon'oglyoeridesr pow 5 incubation tank, or-are-first"broughtttogetherand? tfims" are:distrihuteotunifbrmlizz ihvthedrietf-nom then cooled prior to'the-intro'duotion into them"- ftiitrportionr;ofl't'i'ie-millrpowcber andare-ami'i cuhatiomtanfiz TIT tfiempp'ztratus" shown iitFi'gtablesforflevorrandmhysiczl efieet'whe'n-tfie non uitefi or seriarate c'ooiers? are e'mpjkiyed; one of fattportions ofthe'" powder are dissolved t e which-is oool'ei'"t tinoorpoiatedifi the-skim moisfilreofftfiemouth: 'Ifiefinishe'cf'limxrd er 's:'- "1ine 42. The other parts which are similar to" hiig'myr so'iubiemwaterrand contaihs an"optimum tfio'se 'efFi tire-1 will not he describes? in detaih quantityoffi'ee'ffit. Itis'to-b'eurrderstoodf how b n-t awe ed" on the drawing fiy'flle. same temperature, the milk p2isesint0*a5n' 1 w hat the. fat content and. the extent-"oi referenc'e' nu ereslst applied"to"'the'correspondin'g" hiiomsi s. can he. adjusted within relatively wide A pai'ts of Figure-1*; It will be noted that theuppei: lfr'i'ftsi as her'e'i nti.havetv set forth; and 176- aocorct line", W bh eoniis inethe'eurgetank l9; homogewitfi. the": needi of. perticuiavuses" andt oertitzu-leiw ni'effilfi: andeooler 2ft; isinthecreamhne'passing:

manufactures". fromthe'iseparatorm rm omen-to; tiietter illustrate" the process? for' fieferrihg 'riow t'o'Figme'3; it will beobservecfi the: manufacture of milk? products. 93ccert1=- that theproeedure" equipmentdisciosed" sire:-

ancbrwitfi: th'ii: invention; reference may be Had? substantially the: same as that shown Figure to? the accompanyingdremngs; i'nwfiicfi 2; Withitfie exeeption that twoa fiiditionailt iiic'tibai- Eigure; his" a".'fiowsheet"iflustrst'tiflgwne prone tron-r tanks" are shown: To" the extent that the? dime and; setrofeqniismenti for" preparing" and irw equipment is-the some as? that 'inustratewifi: Fig; cutiazting'imilk'raceordingto"this inventiom u-re 23 similar" reference numera'l's" haveheel-1' Figure 2- inustratew a siiniiw out somewhat empl'byed;

- In addition to the incubation tank 24, a second incubation tank 50 is shown, connected to the skim milk line 42 by a line 5|. The tank 50 also has arecirculating line 52 equipped with a centrifugal pump 53, and a valve 54 corresponding to the valve 21. The tank also includes an agitator or agitators 55. There is also shown in dotted lines a still further incubation tank 60 having a recirculating pipe BI containing a centrifugal pump 62 and a valve 63. This tank is equipped with an agitator or agitators 64, and is connected by a line 65 to the homogenizer 20.

The advantages of the procedure and equipment illustrated in Figure 3 are two-fold. According to this procedure, it is possible to obtain homogenization with a smaller homogenizer since the fat being homogenized is concentrated or reduced in volume. An additional advantage is derived from incubating the cream separately. In some instances, a plant receiving an excess amount of skim milk may proceed to evaporate such excess and produce a skim milk concentrate or some other product while the cream, according to this procedure, is being incubated in the smaller incubating tank. Thereafter, as more raw skim milk is received from the plant, the cream may be dropped into one of the other tanks and mixed with skim milk for conducting the final part of the hydrolysis. In addition, it is frequently desirable to produce a product containing a high amount of free fatty acids, that is to say, in the order of degrees to degrees free fatty acids. When such a large amount of free fatty acids is desired, it is expedient to incubate the cream at a temperature of around 90 F. for a period of from two to four hours and then to drop the cream so incubated into cold, raw skim milk for a completion of the hydrolysis. At 90 F., a free fatty acid degree of around 8 to 10 may be obtained in the fat of the cream within the relatively short period of from approximately two to four hours. Although free fatty acids so hydrolyzed do not exist in the product in the correct ratio between volatile and non-volatile free fatty acids, as the non-volatiles are excessively produced at 90 F., the amount of non-volatile free fatty acids is not so great that it cannot be compensated for during the later and chief hydrolysis conducted in the presence of cold skim milk, that is to say, conducted at a temperature below substantially 50 F. It is found that such practice will result in a free fatty acid distribution within the range desired.

It will thus be seen that by incubating cream at 90 F. for a very short period, more total free fatty acids can be formed than at a lower temperature in a given time, and yet the ratio of the different acids is not greatly affected because a large part of the hydrolysis is carried out at the lower temperature.

Referring now to Figure 4, a storage tank I00 is provided for the milk that has been incubated according to this invention. The milk so stored is pumped by a pump IOI from the storage tank I00 through line I02 into a heater I03 where it is heated to a temperature of approximately 175 F. to 200 F. The milk next passes through line I04 into a second heater I05 where the temperature is raised to from 240 F. to 280 F. It then passes through line I 06 and through a valve I01 and is thus flashed into the tubes of a first effect I08 of a multiple effect evaporator. The evaporator shown is of known design, and it will be observed that the vapors produced in the first effect are fed through line I09 and serve as a source of heat for the second efiect H0. The concentrated milk passes out of the first efiect through line III into the bottom of the second efiect. The milk from the second effect is finally taken through line I I2 by means of pump H3 and is fed to the storage tank H4. The concentrated milk may thereafter be taken from the tank through line I I5 by means of pump I I 6 and fed to suitable spray drying equipment. I20 is a condenser which is connected by pipe IZI to the second effect and serves to condense the water vapors and fatty acids which are collected in the bottom thereof as at I22.

In addition to concentrating the milk, the evaporators shown, and particularly the first efiect thereof, flash off the unwanted excessive volatile water-soluble fatty acids and the volatile water-insoluble fatty acids in amounts as hereinabove pointed out and determined by the feed temperature.

It is to be understood that the evaporator may be of any suitable construction and may .be a single, double, or multiple effect type. If desired, a Vacreator may be used ahead of the evaporator to fiash volatile acids when a vacuum pan I is used instead of a rising and falling film type of evaporator.

The milk collected in tank I I4 usually contains between approximately 30% and approximately 50% solids.

It is to be understood that the ingredient in the milk product here produced which imparts the desirable flavor is the combination of free fatty acids which exist in the desired relative proportions. Consequently, this invention contemplates a milk fat product containing from approximately 2.75% to approximately 8% of the fat present as free fatty acids, or, as stated in degrees, from approximately 15 degrees to approximately 40 degrees in the fat present. Furthermore, as expressed in percentage equivalent weight, calculated as oleic acid, the volatile water-soluble free fatty acids and the volatile water-insoluble free fatty acids, and the nonvolatile water-insoluble free fatty acids should exist in the combination somewhere in the neighborhood of the percentages set forth above, namely, 50.0% for the first group, 28.8% for the second group, and 21.2% for the third group. Of course, these figures are not to be considered as strictly limiting, as reasonable variation from these quantities will still produce a combination which imparts desirable flavor. Expressed in terms of degrees, it will be noted that when a total of 30.4 degrees, which represents 4.42% of the total fat, has been hydrolyzed, the ratio for each group will be 11.1 degrees for the first group, 6.4 degrees for the second group, and 4.7 degrees for the third group, after flashing. Other variations in degrees are hereinaboveset forth and are to be consulted as guides concerning the particular ratio of free fatty acids in each group.

The product of this invention can be utilized in making milk chocolate, in which event from between approximately 20% up to approximately of the milk fat requirements for the manufacture of chocolate can be supplied by utilizing the product of this invention. When chocolate is so made, the other ingredients, such as chocolate, sugar, and any other substances called for in the recipe to be used, can be added according to known procedure now in general use. In other words, the chocolate of this invention can be made like any other chocolate except that as to approximately 100% of the milk fat requirements for the manufacture of chocolate may be supplied by utilizing the product of this invention. Also, from small amounts to 100% of the milk fat requirement of products other than chocolate may be supplied by the product of this invention. However, this invention contemplates the desirability, at times, of diluting the flavor intensity and controlling composition of the product prior to use in a particular manufacture for which it is intended. The additional practice of controlling flavor intensity and composition may be accomplished by adding norm-a1, unincubated whole milk, cream, partially skimmed milk, or nonfat milk after the incubation is substan tially completed. The desired unincubatedmilk substance may be added just prior to flash treatment and evaporation, or such substance may first be evaporated and added in concentrate form to the flashed and evaporated product of incubation, and the resulting concentratemay then be dried or it may be mixed indried. form to the dried productof. thisincubation. However, the incubated portion must be prepared according to the disclosures of the invention in order to provide proper flavor characteristics, even though dilution and changes in composition may bemadeaftertheincubation has been'substantiallycompleted.

What is claimed is:

1. Theprocess of producinga' new mill; product containing milk fat which is capable of imparting a high milk flavor to various food products to which it is added as an ingredient, which comprises hydrolyzing from approximately 15-degr'ees to approximately 40 degrees of freefatty acids in the milk fat by the action, for the most part, of the natural lipase of the milk, while said milk is maintained at a temperature of between approximately 30 F. and 50 F., and thereafter removing from approximately 30% to approximately 4 0f the volatile water-soluble free fatty acids and from approximately to approximately of the volatile water-insoluble free fatty acids.

2. The process of producing a new milk product containing milk fat which is capable of imparting a high milk flavor to various food products to which it is added as an ingredient, which comprises hydrolyzing from approximately 15 degrees to approximately degrees of free fatty acid in the milk fat by the action, for the most part, of the natural lipase of the milk, while said milk is maintained at a temperature of between approximately 30 F. and F., and thereafter removing from approximately 30% to approximately 45% of the volatile water-soluble free fatty acids and from approximately 15% to approximately 25% of the volatile water-insoluble free fatty acids by steam evaporation.

3. The process of producing a new milk product containing milk fat which is capable of imparting a high milk flavor to various food products to which it is added as an ingredient, which comprises hydrolyzing from approximately 15 degrees to approximately 40 degrees of free fatty acid in the milk fat by the action, for the most part, of the natural lipase of the milk, while said milk is maintained at a temperature of between ap- 18 proximately 30 F. and 50 F., and thereafter removing a portion of the volatile water-soluble free fatty acids and a portion of the volatile water-insoluble free fatty acids by steam evaporating said product at a temperature of between approximately 212 F. and 280 F. in a vacuum of from 28 inches of mercury to approximately 30 inches of mercury.- 1

4. The process of claim 1, further characterized in that the hydrolysis is conducted for a period of from approximately sixteen hours to approximately seventy-two hours.

5. The process of claim 3, further characterized in that the hydrolysis is conducted for a period of from approximately sixteen hours to approximately seventy-two hours.

'6: The processof claim 1, further characterized in that the hydrolysis is conducted with a fat concentration of the milk of approximately 12% or less.

'7. Theprdcessof clai-m-3, further chara'ct'erized in, that the hydrolysis is conducted with-a-fat concentration of the milkofapproximately12-%- Orless;

8. The process of claim 1, further characterized in that the milk is first clarified 'ata temperature of between 65 F. and F;

9. The process of claim 1, further characterized in that the milk is homogenized to reduce the particle size of the fat globules thereof to app oximately 3 microns 'or loss before the sa'meis hydrolyzed .L 10. The-process of claim 1, further characterized in that hydrolysis is carried out withagita- 11. The process of claim 1, further character-- ized in that the milkproduct'is first clarifiedat a temperature of between 65 F. and-90 F. and subsequently homogenized to reduce the particle size of the fat globules 'to approximately 3 microns or less and at a temperature of not toexceed F. leaving the homogenizer. v 7 I 12; The process of claim 1, furthereharact'er ized in that the milk product is first clarified at a temperature of between 65 F. and 90 F., and subsequently homogenized to reduce the particle size of the fat globules to approximately 3 microns or less and at a temperature of not to exceed 120 F. leaving the homogenizer, and further characterized in that the hydrolysis is conducted with agitation.

13. The process of claim 3, further characterized in that the milk is first clarified at a temperature of between 65 F. and 90 F.

14. The process of claim 3, further characterized in that the milk is homogenized to reduce the particle size of the fat globules thereof toapproximately 3 microns or less before the same is hydrolyzed.

15. The process of claim 3, further characterized in that hydrolysis is carried out with agitation.

16. The process of claim 3, further characterized in that the milk product is first clarified at a temperature of between 65 F. and 90 F., and subsequently homogenized to reduce the particle size of the fat globules to approximately 3 microns or less and at a temperature of not to exceed 120 F. leaving the homogenizer.

17. The process of claim 1, further characterized in that the milk product is first clarified at a temperature of between 65 F. and 90 F., and subsequently homogenized to reduce the particle size of th fat globules to approximately 3 microns or less and at a temperature of not to exceed characterized in that the hydrolysis is conducted with agitation.

18. The process of producing a milk powder containing milk fat capable of imparting a high milk flavor to various products to which it is added 'as an ingredient, which comprises hydrolyzing milk fat according to claim 1, and thereafter spray drying said product to reduce the water content thereof to approximately 4% or lower.

19. The process of producing a milk powder containing milk fat capable of imparting a high milk flavor to various products to which it is added as an ingredient, which comprises hydrolyzing milk fat according to the process of claim 1, thereafter spray dying said product to reduce the water content thereof to approximately 4% or lower, and thereafter refining said product to increase the so-called free fat content thereof to a point in excess of approximately 4%.

20. The process of producing a milk powder containing milk fat capable of imparting a high milk flavor to various products to which it added as an ingredient, which comprises hydrolyzing milk fat according to claim 3, and thereafter spray drying said product to reduce the water content thereof to approximately 4% or lower. I v

21. The process of producing a milk powder containing milk fat capable of imparting a high milk flavor to various products to which it added as an ingredient, which comprises hydrolyzing milk fat according to the process of claim 3, thereafter spray drying said product to reduce the water content thereof to approizimately 4% or lowerfand thereafter t said product to increase the so-called free fat co tent thereof to a point in excess of approximatel 41%.

22. A food product, comprising milk fat l1y-- drolyzed to a free fatty acid degree of from approximately 15 degrees to approximately 40 degrees, and in which hydrolyzed fat in three classes of free fatty acids exist in the ratio of approximately 5:3:2- by weight when measured according'to the method set forth in the specification and when such fatty. acids are expressed in terms of equivalent'weight. of 'oleic acid, in which the classes of free fatty acids are present in amounts to give from substantially 15 degrees to substantially 6 degrees of volatile water-soluble free fatty acids, or from substantially 13 degrees to substantially 5 degrees of volatile water-insoluble free'fatty acids, and from substantially 5 degrees to substantially 2 degreesof non-volatile water-insoluble free fatty acids.

23. Afood product of the type defined. in claim 22, further characterized in that such milk fat is incorporated with milk solids not fat.

24. A spray dried milk product havinga moisture content of less than approximately containing milk solids not fatan'd modified milk fat of the type defined in claim 22.

25. An improved milk chocolate having from approximately 20% to approximately 109% of its milk fat requirements composed of the milk fat product defined in claim 22.

26. The process of improvingthe flavor of milk chocolate, which comprises adding thereto from approximately 20% to approximately of its milk fat requirements of the milk fat product defined in claim 22.

CLAYTON A. KEMPF.

JOY SU'IHERLAND NEIDLING-ER. AUBREY P. 'S TEWART, J R.

PAUL F. SHARP.

References Cited in the ills of this patent UNITED STATES PATENTS Number Name Date 668,253 Campbell Feb. 19, 1901 1,966,460 Otting 'July 1'7, 19-34 2,169,278 Otting Aug. 15, 1939 2,519,833 Hallqvist Aug. 1950 2,539,125 Froding Jan. 23, 1951 

1. THE PROCESS OF PRODUCING A NEW MILK PRODUCT CONTAINING MILK FAT WHICH IS CAPABLE OF IMPARTING A HIGH MILK FLAVOR TO VARIOUS FOOD PRODUCTS TO WHICH IT IS ADDED AS AN INGREDIENT, WHICH COMPRISES HYDROLYZING FROM APPROXIMATELY 15 DEGREES TO APPROXIMATELY 40 DEGREES OF FREE FATTY ACIDS IN THE MILK FAT BY THE ACTION, FOR THE MOST PART, OF THE NATURAL LIPASE OF THE MILK, WHILE SAID MILK IS MAINTAINED AT A TEMPERATURE OF BETWEEN APPROXIMATELY 30* F. AND 50* F., AND THEREAFTER REMOVING FROM APPROXIMATELY 30% TO APPROXIMATELY 45% OF THE VOLATILE WATER-SOLUBLE FREE FATTY ACIDS AND FROM APPROXIMATELY 15% TO APPROXIMATELY 25% OF THE VOLATILE WATER-INSOLUBLE FREE FATTY ACIDS. 